Quick answer: Heat speeds up battery ageing, especially when the battery is also sitting at a high charge. Park in the shade when you can, avoid leaving the car at 100% or near empty for long periods, follow the charge limit your car recommends for its battery type, and keep most charging slow and at home.
Your car's battery management system does a lot of work to protect the battery. It heats and cools the pack and stops it charging too fast when it's hot. A few habits on your side help it along, and they matter more in an Australian summer.
Why heat matters
The chemical reactions that slowly wear out a lithium-ion battery run faster at higher temperatures. A battery that spends a lot of time hot, and especially hot and full at the same time, tends to lose capacity faster than one kept cooler.
You don't need to avoid driving on hot days. The goal is to reduce the hours the battery spends sitting hot and full when it doesn't need to.
Park in the shade when you can
A garage, carport or shady spot makes a real difference on a 40-degree day. The car may also use energy to cool the battery while it's parked in the sun, which is energy you'd rather keep for driving.
Don't leave it sitting full or empty
Charging to 100% right before a long trip is fine. What's best avoided is leaving the car at 100% for days, or running it very low and leaving it there. Set your charge to finish close to when you leave, if your car or charger allows it.
Know your battery type: LFP or NMC
Two battery chemistries are common in EVs sold in Australia, and they like different charging habits.
- LFP (lithium iron phosphate): used in many BYD models and in some versions of the Tesla Model 3, Model Y and MG4. Manufacturers often recommend charging LFP batteries to 100% regularly, because it helps the car keep its range estimate accurate. Tesla, for example, recommends charging LFP cars to 100% at least once a week.
- NMC (nickel manganese cobalt) and similar chemistries: common in many other EVs. A daily charge limit of around 80–90% is commonly recommended, with 100% saved for longer trips.
Your car's manual or app tells you which battery you have and what limit the manufacturer recommends. Their advice comes first.
Fast charging in summer
Public DC fast charging is fine when you need it. The car slows charging down to protect a hot battery, which is why fast charging can feel slower on a hot afternoon. If your car can precondition the battery on the way to a charger, use it. For everyday driving, slower charging at home is the gentlest option.
Keep an eye on it
Habits help, but they don't tell you how your battery is actually doing. A battery health check reads the state of health, every cell group, temperatures and stored faults, so you have a measured baseline. Checking once a year, or before the battery warranty ends, lets you spot a change early.